1. Field of the Invention
This invention relates to an injection device of a die casting machine, which includes an injecting cylinder operated with pressurized oil fed from a hydraulic source and a servo valve controlling the injection speed and pressure of the injecting cylinder by controlling flow of the pressurized oil that flows from the injecting cylinder.
2. Description of the Related Art
A die casting machine includes an injection device in order to inject molten material into a cavity of a mold. The injection device includes an injecting cylinder in which a piston, being coupled to a piston rod having an injection plunger at the end of the piston rod, is slidably thrust into the cylinder body.
The injection speed of the injecting cylinder is controlled by controlling the flow of the pressurized oil that flows from the injecting cylinder by using a servo valve.
The conventional injection device of the die casting machine is adopted with a mode in which the pressurized oil is controlled at the entrance side, and further, as cited in Japanese Patent Application Laid-open No. Hei 6-39516, the servo valve is far away from the injecting cylinder, with the result that a long channel connecting the servo valve and the injecting cylinder is formed.
In consequence, the conventional injection device of the die casting machine has a disadvantage in that resistance in the channel is large, which is caused by the long formed channel connecting the servo valve and the injecting cylinder, having a large distance between each other.
Naturally, the pressurized oil cannot flow into the servo valve in large quantities, whereby the conventional injection device has a poor quality of response and is not amenable to change the injection high speed control from the feedback control by either extremely low speed injection or an injection low speed.
An automaker or the like has expected product parts with reduced weight, in order to produce the product, however, the quick, accurate quality of response of the injection device is required, whereby the conventional injection device has limitations for filling the need for reducing weight.
It is an object of the present invention to provide the injection device of the die casting machine, which has a lower resistance in the channel and a quick, accurate quality of response.